OK Tony
Here is some notes by me:
-some texture are missing/not correct (renault, rebaque,...)
-some cars missing (fittipaldi (not sure wich version, F5A?), kauhsen
WK004/WK005, alfa 177, ensige N177/N179 and maybe some other variations of other teams)
-some tweaking (remember that lotus at one or more tracks have wrong helmet position)
-tracks :D (but that is well known issue in GP4)
I think that beta have some others bugs but cant remember all. I play it for long time. But for beta it was good and enjoyable
Anyway, I have one sugestion; Maybe few wheels/rims can be includes in mod (if it is not too big job to make them) or when one team is selected that all teams have wheels like selected team/car (something like steering wheel in some mods).
Hope that final product will follow your previous mods, but I have no doubts about that
Good luck mate